This application is to request funds to purchase the Nikon Structured Illumination (SIM) super-resolution microscope. The system is configured to be a dedicated super-resolution fluorescence imaging system. It will be the first super-resolution microscope at Northwestern University. The various features built into the system are designed to be highly versatile in a heavily used imaging core facility with a multitude of applications. Th purchase of this important equipment will directly enhance the work of at least twelve NIH-funded major users, as listed in the application. The SIM system is crucial in address a urgent paucity of instrumentation capable of delivering sub-diffraction resolution required to fill the information gap that has long-existed between light and electron microscopy. The availability of this system will allow the federally funded investigators to immediately enhance their NIH-funded research to gain hitherto unavailable ultrastructural information, to begin performing cell biological experiments with greater precision and to formulate and test new hypotheses. Identified by Nikon as the SIM super- resolution imaging center in the Midwest, we have tested this instrument on-site using specimens directly related to the NIH-funded work. We present here preliminary data for the various applications we propose to perform on the system. The preliminary results presented include several high impact data that are now being prepared for publication, highlighting the scientific impact and suitability of the instrument, as well as our technical expertise to operate the system.